On the upland side (top of bluff), slope failures may occur as a result of water buildup in the soil. This can happen naturally, or as a result of development activities, clearing of vegetation, and modification of site drainage. At the bottom of a bluff, waves and fluctuating high water levels due to tides can undercut the toe of the bluff and cause collapse. In both cases, bluff erosion is usually due to a combination of water and gravity, with the encroaching influence of development adding to the natural erosion. Our rainy climate keeps our soil moisture levels high the majority of the year, and can be at or near the saturation point during the wet months of winter.